1. Field of the Invention
The present invention relates to an apparatus for treating a large amount of food for denaturation and sterilization under high pressure at low temperatures.
2. Description of the Prior Art
There have been active studies on the application of high pressure to food for denaturation, sterilization, and oxidation control. The denaturation of jam by high-pressure treatment has been put to practical use. In addition, the latest development is intended to enhance the effect by combining high pressure with high temperature or low temperature.
The existing high-pressure apparatus for production or research is of the piston type. It usually undergoes temperature control by the circulation of hot water or cooling medium around the high-pressure vessel.
When the treatment of food under high pressure comes into general use in the future, the apparatus of the piston type will be replaced by a new one which is designed such that the high-pressure vessel is supplied with a pressure medium by a pump from an external source as shown in FIG. 6. Referring to FIG. 6, there is shown a high-pressure vessel 20, which, in combination with top and bottom closures 21 and 22 fitted thereto, forms a high-pressure chamber (treating chamber) 23. An object 24 placed in the treating chamber 23 is pressed by a pressure medium introduced thereinto from a pressure medium tank 25 by a pump 26. During operation, the high-pressure vessel 20 is cooled externally by circulating a cooling medium from a cooling unit 28 through a jacket 27 attached to the periphery of the vessel 20. Incidentally, there are shown a pressure reducing valve 29 and a press frame 30.
The apparatus shown in FIG. 6, however, has a disadvantage of making it necessary to manage a large amount of thermal energy for temperature control. This disadvantage leads to a high production cost. In other words, cooling by a cooling medium is poor in cooling performance and heat efficiency.
Moreover, the conventional apparatus presents the difficulty of controlling the temperature of pressure the medium. It also presents a difficulty that if the pressure medium tank is at normal temperature, the pressure medium introduced into the vessel prevents the cooling of the vessel.